Adjusting gearing for variable pitch propellers



H. EBERT April 23, 1935.

vADJUSTING GEARING FOR VARIABLE PITCHPROPELLERS Filed Oct. 28, 1933 Apr. 23, 1935 irs Smith-S PATENT oFFlcs ADrUs'riNG GEARnvG rolt v rrren Pnormanits Application Qctober 28, 1933, Serial No. 695,683

, Germany November 2, 1932 t lillaims.

This invention relates to adjustable gearing for variable-pitch propellers, more particularly on aircraft, consisting of a drive gear or gearing, rigidly connected to the source of power, and a gear capable of angular displacementI relative to the drive gear and loose on its shaft and interconnecting gearing for angular adjustment of the propeller blades on their axes.

For varying the pitch of pi'opellers while running, a number of types of devices'are known, which may be divided, in point of principle, into the following three main groups.

(1) 'Adjusting devices by means of whichthe propeller blades are adjusted by the displacement of a member .in the longitudinal direction of the propeller shaft. Y

2) Adjusting devices in which the adjustment is edected automatically, for example by the centrifugal action of structural members which ro- 20 tate with the propeller.

(3) Adjusting devices in which the adjust'nrientof the -propeller blades is obtained by purely rotational motion, for example by means of gearing.

The types comprised under 1 are generally simple, but are attended with the drawbacks of limited range of adjustment andtoo great structural length. Y i

The types comprised under 2 are not applicable to all purposes.

On the other hand, those in group 3 possess the advantages of unlimited range of adjustment and small structurallength. The present invention as hereinafter described and illustrated, belongs to this group.

Heretofore adjusting gearing of the type under group 3 has been constructed as a planetary gear;- ing, i. e. as a gearing in which the planetary gears turn around the propeller shaft and mesh with a gear with outer teeth xed to and rotating with the propeller shaft and with an adjustable gear with inner teeth. The shaft of these planetary gears rotates .constantly around the propeller shaft. The adjustment is made by connecting two of these planetary gearings in series. For this purpose the planetary gears of one train of gears are made capable of angular displacement relative, to those of thel other train of gears on the planetary shaft. The adjustment can then 50 be made by turning'` the gear with inner teeth so that the planetary gears of one planetary gea. ing are turned angularly relative to those of the other planetary gearing on the common planetary shaft. It is only in this way that the loose gear with inner teeth is displaced angularly relative (ci. itt-ies) to the xed gear on the propeller shaft and adjustment thereby accomplished.

' In contrast with the foregoing, in the adjusting v gearing, according to the present invention, a

gearing is provided with two connecting gearings 5` or groups of connecting gears, the shafts of which do not take part in the revolution of the main drive shaft, and which mesh on the one hand with the fixed drive gear and on the other hand with the loose adjusting gear. The connection between the two gearings or groups of -gearings is made by an intermediate gear loose on the shaft of the fixed drive gear.

It is important, therefore, that the two gearings or groups of gearings, in contrast with the known planetary gearings, are connected` together by a common intermediate gear freely turning on the propeller shaft, while the gearing shafts are mounted in a xed manner. The adjustment is made in the device according to the invention by swinging a-gearing shaft around the axis of the main. drive shaft. The advantage of the adjusting gearing according to the invention is that the small gears that run at very high speeds in aircraft engines need not turn around the main drive shaft. In this way the bearing of these gears is simplified considerably so that it 'can be made lighter and above all more sure in operation.

The gearing of the present invention provides a positive unlimitedrange of adjustment which is accurate and independent of the engine speed.

v In order more clearly to understand the invention, reference will be made to the accompanying drawing, which illustrates diagrammatically and by way of example, several embodiments of the variable gear according to the invention.

Fig. 1 illustrates a form of construction in which the propeller shaft is integral withthe engine shaft and the adjusting gearing is grouped around the propeller shaft.

Fig. 2 shows a diagram of the adjusting operation. y

Fig. 3 relates to the case where a transmission gearing is provided between the engine and the propeller shaft. c

Fig. 4 shows a form of construction especially suitable for ships screws.

In Fig. 1, the adjusting gearing is housed in an enclosed gear case located between the power 50 unit and the propeller and concentric with the propeller shaft l. It consists of two relatively rotatable halves, one of which 2 may be connected to `the engine, Whilst the other 3 is adapted to be rotated, for adjusting the propeller, by 55 means of a hand wheel or crank E as shown in` the drawing. Each'half of the gear case is provided with one or more fixed pins 5 and 6 disposed in a circle around the engine shaft and carrying the hollow shafts-which represent-in principle, two countershafts operating in seriesof .the pinions 1 'and 8, 9 and Ill respectively. These pinions cooperate with the other pinions in such a nanner that, when the propeller is not adjusted, the rotation of a pinion II-which is keyed on therengine shaft-through an inter mediate pinion I2, adapted to rotate in relation to the engine shaft, is=transmitted to an idle pinion I3 also mounted on the engine shaft, so that this latter pinion rotates with the same angular velocityas the engine shaft, that is to say, is stationary in relation tosaid shaft. Now, since this pinion I3 is connectedl-for example' through cone or worm gearing |4-with the propeller blades I6, which are adapted to turn about A their longitudinal axis to the hub I5, a positive twist is imparted tothe propeller blades directly the pinion I3 is adjusted in relation to the engine shaft.

This adjustment is effected by turning the half 3 of the gearv case through a definite angle by means ofthe hand crank 4. By this movement, one 6r of the two countershafts is turned, in relation to theother shaft 5, around `the axis of the engine shaft, relative twists being produced, as shown in Fig'. 2. Since these areindependent of the-speed of the engine shaft, and therefore must also be identical both when the engine 4is at rest oris running at any speed, they are represented, by way of example, when the engine is at rest. At thesame time, the pinion II keyed on the engine shaft is at rest, so that, even on the half 3 of, the gear case being' turned, the inter' mediate pinion I2, connected therewith through the gears 1, 8 must also be stationary. vThis implies that, on theipin 6 being turned throughthef angle u, the point of application A of the pinion 9 in the intermediate pinion I2, mustbe re- I garded 'asa xed point and consequently, in ac- -cordance with the motion diagram shown in Fig. 2, the pinion I3 must undergo a relative displacementthrough the angle a result rthat is equivalent to a corresponding adjustment'of the propeller. y

When the engine is in operation and the propeller shaft I therefore has a definite number of revolutions with the gear II ixd on the same, the loose gear'` I3 has thenthe same number of revolutions vdue to introduction ofthe con.- n'ecting gearing'1, 3, 9, Ill .and the loose intermediate gear |.2 forming a'connection between the drive gear Il of the shaft l' and the gear I3. A relative angular displacement between the gears I3 and II is produced only when an angular displacement of the half 3 of the housing and consequently of the gearing 9, I0.' is produced by means of the adjusting gearing 4 -in the way described above. w

If an increasing or reducing gear is already presentits pinions may be utilized for the variable gear of the present invention. A n example of this is shown in Fig. 3. 'I'he pinions 23 'and 24 provided for transmitting power from the engine shaft I to theseparate propeller shaft 2| are incorporated in the variable gear. The shaft f of the one countershaft of the embodiment described with reference to Figs. `1y and 2, now serves also as the driving shaft, the arrangement being otherwise-in principle-the same as before, except that, for reasons of convenience, the intercase half 3 which is adapted to be rotated around the propeller shaft by means of the hand crank 4.

vThe transmission gears 23, 24, are linked into the adjusting arrangement the connecting gears 23 and 21 corresponding to the connecting gears 1, 8 of Fig. 1.' The loose intermediate gear I2 of Fig. 1 is'replaced in Fig. 3 by two gears 26 and 26 mounted on a hollow shaft, i. e. loose on the shaft 2|'. Here also the connecting gears 23, 21, Band I0 again do nottake part in the.

`circling of shaft2| and the connection between the drive gear 24 and the loose adjusting gear I3 is made by the loose intermediate gearing 25, 26.

The embodiment of Fig. 4 Ashows the application of an auxiliaryl shaft 3| for the variable gear, an arrangement which may be ofadvantage in the case of marine propellers with propeller shafts of very large diameter, since it allows a spacesaving side structure of the adjusting arrange-` ment' beside the screw shaft.I Inl the case of Fig. 4, the adjustable part 3 of the housing of Figs. 1 and 3 is replaced by a gear 3'-l that is capable of angular displacement on the secondary shaft 3| by means of the drive k4, and for coni nection between secondary shaft 3| and screw shaft I', the gears I8, I9 areprovided meshing with the fixed drive gear Il'and the loose adjusting gear |3.` Nothing,therefore, is changed inthe s' basic principle of the adjusting arrangement according to Fig. 1.

Itis to be understood that the invention is not 'restricted to the particular constructions which have been illustrated as typical embodiments of the invention, and that various changes may be made without departing from' the spirit of my invention as set forth in the following claims.

I claimz- 1. Adjusting gearing for variable pitch propellers consisting of a drive shaft, a drive gear rigidly co ected to said drive shaft, a gear capable of angular displacement relative'to the drive gear andloose on said drive shaft, two connecting gearings meshingon the one hand with the drive gear and on the other hand with said gear capable of angular displacement, an intermediate gear connecting said two connecting seminal.v

and means for angular displacementl of one of said two connecting gearings. l

2. Adjusting gearing according to claim 1 in ewhich the intermediate gear is rotatably mounted -on the drive shaft. f i v 3. Adjusting gearing according to claim 1 in which' the intermediate gear is mounted on a shaft parallel to the drive shaft.

4. Adjusting gearing for variable pitch propellers comprising -a propeller shaft having a propeller hub xed thereto,- propeller blades each having a root portion mounted on said hub for angular adjustment, anv adjusting shaft coaxial with said propeller shaft and'capable of relative rotation with respect thereto, gearing between said adjusting shaft and said blade roots for' rotating said blades upon relative rotation' alia-com" imacat tively stationary stub shaft, connecting gearing rotatably mounted on said stub shaft for driving said adjusting shaft from said sun wheel and at the same speed as said propeller shaft, and means adjustable at will for displacing said relatively stationary stub shaft angularly with respect to the axis of said sun wheel, thereby to effect a relative rotation of said adjusting shaft with respect to said propeller shaft.

5. Adjustable gearing as claimed in claim 4, wherein said propeller shaft and said drive shaft are integral portions of the same shaft.

'6. Adjustable gearing as claimed in claim t,

wherein said propeller shaft and said drive Shaft are integral portions of the same shaft, and said sun wheel is rotatably mounted on the said integral shalt. j

7. Adjustable gearing as claimed in claim 4, wherein said sun wheel is rotatably mounted on said propeller shaft, and a gear drive connects said drive shaft and said propeller shaft.

8. Adjustable gearing as claimed in claim 4,

wherein said sun wheel is mounted on a shaft 10 

